import { fetchRequestHandler } from '@trpc/server/adapters/fetch'
import { appRouter } from '@/server/routers/_app'
import { createContext } from '@/server/context'
import { checkRateLimit } from '@/lib/rate-limit'

const RATE_LIMIT = 100 // requests per window
const RATE_WINDOW_MS = 60 * 1000 // 1 minute

function getClientIp(req: Request): string {
  return (
    req.headers.get('x-forwarded-for')?.split(',')[0]?.trim() ||
    req.headers.get('x-real-ip') ||
    'unknown'
  )
}

const handler = (req: Request) => {
  const ip = getClientIp(req)
  const { success, remaining, resetAt } = checkRateLimit(`trpc:${ip}`, RATE_LIMIT, RATE_WINDOW_MS)

  if (!success) {
    return new Response(JSON.stringify({ error: 'Too many requests' }), {
      status: 429,
      headers: {
        'Content-Type': 'application/json',
        'Retry-After': String(Math.ceil((resetAt - Date.now()) / 1000)),
        'X-RateLimit-Limit': String(RATE_LIMIT),
        'X-RateLimit-Remaining': '0',
      },
    })
  }

  return fetchRequestHandler({
    endpoint: '/api/trpc',
    req,
    router: appRouter,
    createContext,
    responseMeta() {
      return {
        headers: {
          'X-RateLimit-Limit': String(RATE_LIMIT),
          'X-RateLimit-Remaining': String(remaining),
        },
      }
    },
    onError: ({ path, error }) => {
      console.error(`tRPC failed on ${path ?? '<no-path>'}:`, error.message)
    },
  })
}

export { handler as GET, handler as POST }